Pick up the drained tuna. Cut the mozzarella into thin even slices and then quarter. Roughly chop the egg. Peel the tomato and cut into even cubes. Slice the cucumber thinly.
Chop the onion and squeeze the garlic. Put in a bowl, add vinegar and oil and mix well, salt and pepper. Then mix with the salad ingredients and distribute on 4 plates. Place the basil leaves on top as a decoration.
This refreshing salad can be prepared 2-3 hours in advance in the fridge without the egg, tomato or cucumber covered.